function sample_x = init_sample(num_initial, num_vari, len_vari)
sample_x = zeros(num_initial, num_vari, len_vari);
for i = 1 : num_initial
    for j = 1 : num_vari
        for k = 1 : len_vari
            if rand > 0.5
                r = 1;
            else
                r = 0;
            end
            sample_x(i,j,k) = r;
        end
    end
end
end